Carrier telegraph circuit



H. A. AFFEL.

CARRIER TELEGRAPH CIRCUIT. APPLICATION FILED oc T.21. 1920.

1,402,991. Patented Jan. 10,1922;

INVENTOR EJ124179; BY Wu ATTORNEY UNITED STATES HERMAN A. AFFEL, BROOKLYN, NEW YORK, ASSIGNOR T0 AMERICAN TELEPHONE PATENT orrica.

AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

CARRIER, TELEGRAYH CIRCUIT.

Specification of Letters Patent. at t Jan, 10, 922,

Application filed October 21, 1920. Serial No. 418,483.

To all whom it may concern:

Be it known that I, HERMAN A. Armin, residing at Brooklyn, in the county of Kings and State of New York, have invented certain Improvements in Carrier Telegraph Circuits, of which the following is a specification. This invention relates to signaling systems and, more particularly, to signaling systems in which telegraph signals are transmitted by means of carrier currents.

One of the objects of this invention is to provide an arrangement whereby carrier signals may be translated into carrier frequencies for transmission and whereby received carrier frequencies may be translated into low frequency telegraph signals. A further object of the invention is to provide a system of the character above described, in,

which the telegraph apparatus shall be as simple as possible, and the number of relays shall be reduced to minimum.

Other and further objects of the invention will be clear from the following description,

when read in connection with the accompanying drawing, Figures 1 and 2 of which are simplified circuit diagrams of two forms of the invention. I

Referring to Figure 1, ML designates a main transmission line over which carrier currents may be transmitted. A transmittingchannel TL and a receiving channel EL are associated with said main line ML. In order that the channels may besubstantially conjugate, the receiving channel BL is associated with the main line ML through a balanced transformer arrangement of wellknown construction and the line ML is balanced by means of the line MN. The transmitting channel TL includes carrier transmitting apparatus conventionally indicated at T. This transmitting apparatus may assume various forms but, if the system is a multiplex system, should include some selecti'ng means, such as a tuned circuit, a source of carrier frequency, and means for inter-v rupting or modulating the carrier frequency, in accordance with the telegraph signals. As illustrated, a transmitting relay 11 is pro vided for, for interrupting the carrier frequency directly by means of its contact, or for modulating the carrier frequency in any well-known manner, by means of the circuit controlled by its contact.

The receiving channel RL includes rethe detected signal impulses.

ceiving carrier apparatus conventionally'indicated at R. This apparatus may likewise assume a number ofdiiferent forms, but if the system is to be multiplex, it should include some selecting arrangement, such as a tuned circuit and a detector or other arrangement for detecting the telegraph signals from the carrier current. A receiving relay 12 may be controlled by the detector in anysuch a manner that it will respond to In order that the carrier apparatus may be associated with a telegraph station at some distance, a threewire circuit is provided, including conductors 13,114 and 15. The transmitting telegraph station includes a transmitting key Q anda sounder S. In the circuit arrangement illustrated in Figure lythe system is arranged for full duplex'operation, so that the transmitting and receiving operation may take place simultaneously and independently. F or this purpose, the transmit- I gized to interrupt or modulate the transmis;

sion of the carrier frequency by means of the carrier apparatus, to the main line ML. The received carrier currents from the line ML are detected by means ofthe carrier apparatus R, thereby energizing the receiving relay 12 which, in turn, opens and closes the circuit extending over the wire 15 through the sounder S and back over the wire 14% to the battery B. The sounder S, therefore, responds to the signals received by the rela 12.

l igure 2 illustrates the apparatus as ar ranged for half-duplex operation, in which sending and receiving cannot take place sepsarately. The only change required, in order to convert the apparatus from a full-duplex to a half-duplex, is to include the key K in the wire 14, instead of in the wire13.

The operation is as follows:-Norrnally, the carrier is transmitted so that the car- VWl-llflGSPOllCi to the received signal.

riercurrent received from the distant station holds the receiving relay l2 energized. Vith the key K closed, the circuit of the sounder S is completed and the sounder is held energized. 1 The circuit of thetransn'iitting relay 11 is'also completed and the relay 11, by maintaining its contact in closed condition, causeslthe continuous transmission of the carrier frequency by means of the transmitting apparatus T. Iii the operator atvthe station illustrated desires to transmit by interrupting the key 7K, each time the key. isinterrupted,the local sounder S \vill respond and, atthe same time, the

transmitting relay will be de energized to interrupt or modulate the carrier frequency.

If the distant station is transmitting, the key K must be maintained closed undreceiving relay 12, in response to the signals detected from the carrier frequency transmitted from the distant station, willinterruptthe circuit ofrthe sounder S, so that it Should'the operator, while a signal ing received, desire to break in or interrupt, for the purpose of sending to the distant station, the key is: will be held open for an interval. Thisopens the circuit of the sounder S, so that it nolOnge-r responds to the receiving relay 12 and, the same time,

tie-energizes the transmitting relay 11, so

that the carrier-frequency is either not transmitted (iris/changed in amplitude, de- J is benal. i s long as the relay 12 is de-energized,

the circuit of the sounder S will be held open, and the operator who is sending by manipulating the key .12 will understand that a break signal is being received, by observing that the sounder S no longer respends to the actuation of the key.

It will be obvious that the general principles herein disclosed may be embodied in many other organizations Widely different from those illustrated, without departing; from the spirit of theinv'ention, as 'defiiied in the following claims. What is'claimed is: y

1. In a signaling system, a carrier transmitting channel, a carrier receiving channel, a receiving relay associated with said carrier receiving channel, a three wire low frequency telegra'ph circuit extending to a subscribers station, key, atransmitt-ing relay for controlling saidcarrier transmitting'channel in. one Wire, a subscribers sounder included in .a second Wire, and the continuity of said Wire being controlled by thereceiviug relay, and a common source of current for the transmitting relay and the receiying sounder in the third W re;

2. In a signaling system, a carrier trans? mitting channel, afcarrier rece nel, a receivin g relay associated with said carrier receiving channel, athree-wire low irequency telegraph/circuit extending to a subscribers statlon, a transmitting relay for controlling said carrier transmitting chan- ,nel 111 one WLIO, asubscri-bers sounder in-. cluded n: a second wire,and the continuity of said Wire being controlled by the receiv ing relay, and a common source of current for the. transmitting relay and the receiving sounder in the third Wire, and a trans mitting key included in said first ire 7 In testimony whereof, I have signed. my name to this specification this 19th day o f Oct-ober, 1920. V,

HERMAN AFFELQ 

